[alloysteel]

There is still cowpox in America. I know, I have handled cows, and had this brief outbreak of pustules on my hands. In fact, smallpox is apparently a mutant form of cowpox, or camelpox or some other similar animal viral infection, that happened to become extremely virulent and largely affects only humans. Apparently it appeared only a few hundred years ago, did its devastation on an ignorant population, and was finally cornered and driven into near oblivion, existing as of today only as spores in a repository somewhere (hopefully, not in al-Qaeda's arsenal).

[Old Student]

Information I've seen on smallpox indicates it interfered with construction of the pyramids. That is more than a few hundred years ago. (of course, there is a LOT of misinformation out there, also. I believe mine came from the JAMA site.)